Abstract
Shielding of small portions of the hematopoietic system provides protection against the lethal effects of whole-body irradiation in the midlethal dose range. Transfusion of either whole blood or transplantation of hematopoietic tissues protects to some degree in every mammalian species studied.
Manipulation of the radiation dose, time of transplant and recipient treatment with immune suppressors leads to some success in transplants between species. The probability of acceptance of an allograft is inversely related to the number of histocompatibility differences. Hence, in identical twins with no antigenic differences there should be 100% takes. Several investigators (1-4) have followed Atkinson (5) in attempting transplants between a normal individual and his whole-body irradiated leukemic identical twin. A logical extension of identical twin donor-recipient matching is the autologous transplant. The patient serves as donor and recipient with an interim treatment of radio or chemotherapy. This method has been used with varied success in a number of clinical situations (3, 6). Experience has shown that in most radiation incidents patients have received a partial body or nonuniform exposure in which there exist areas of relatively unexposed marrow. These areas can be predicted by depth-dose studies and proven by marrow aspiration. In such cases the question is how best to aid the individual in reseeding his aplastic marrow from the shielded and intact marrow pool. Rudakov et al. (7) have shown that the introduction of a needle puncture into one or both femurs of irradiated rats led to a decrease in mortality. This effect could be increased by flushing with saline. Weinstein (8) demonstrated a similar effect by the intramedullary mixing of marrow by a trocar inserted into the shielded rat tibia.
Several investigators (9, 10) have compared the protective effect of shielded marrow to the injection of an equivalent amount of marrow cells.
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